Use of the fractal dimension for porosity modification in aluminum foams manufactured using space holder particles

Abstract

The effect of space holder particles (SHP) fractal distribution on the porosity of aluminum foams manufactured by infiltration is studied in the present work. Physical models were used to estimate aluminum foam porosity, simulating SHP distribution for bimodal mixtures with different particle sizes and relative quantities. Results of these models were compared with mathematical models and the results obtained for experimental aluminum foams manufactured using a 332 Al-alloy base material and NaCl grains as SHP. Experimental foam structural characterization was carried out using image analysis to obtain porosity, density, wall thickness and fractal dimension, while mechanical characterization focused on the compressive Young modulus. Results show that it was possible to manufacture foams with different fractal porosities and a wide variety of unit cells, reaching a maximum of ? 68%. It was also found that pore wall thicknesses significantly decreased with the increase in the fine particles fraction. Besides, all the models presented a peak with a maximum porosity, whose values increased and shifted to low fine particles fraction with the increase in the sizes ratio. This behavior was also observed for the experimental foams with low particle size ratio. Nevertheless, for higher size ratios porosity showed an irregular behavior attributed to the mixing process.

Sound Absorption Performance and Mechanism of Aluminum Foams with Double Main Pore‐Porous Cell Wall Structure

“…[29,30] In contrast, Figure 5b,e shows the 5# DMP-PCW aluminum foam featuring two different sizes of main pores, where the smaller main pore size predominates. [31,32] The small main pores separate the large main pores and prevent the formation of a network of connections between the large main pores. Furthermore, a large number of cell wall pores are formed within the large main pores, which increases the connectivity of the pore structure.…”